Rhizomes creeping, thick. Leaves linear, 20--60 cm × 5--13 mm, midvein obscure. Flowering stems sometimes with a short branch, 40--60 cm, solid, 1- or 2-leaved; spathes 3, green, often reddish at base, lanceolate, 5--7 × ca. 1 cm, 2-flowered, apex acuminate. Flowers bluish violet or white, 6--7 cm in diam. Perianth tube 8--10 mm; outer segments obovate, claw with conspicuous, brown reticulate pattern on yellow background; inner segments erect, narrowly obovate, 4--5 × ca. 1.5 cm. Filaments white, ca. 3 cm; anthers yellow. Ovary 1.5--2 cm × 3--4 mm. Style branches ca. 3.5 cm × 5 mm. Capsule ellipsoid-cylindric, 3.5--5 × 1.2--1.5 cm, 3-angled; fruiting pedicels equal, long. Fl. May--Jun, fr. Jul--Sep.

Damp meadows, sunny pond banks, mountain stream banks, hillsides; ca. 500 m. Heilongjiang, S Jiangsu, Jilin, Liaoning, Nei Mongol [Japan, Korea, Mongolia, Russia].